The invention involves an intermediate repeater for a communication network for the reception and forwarding of frequency multiplexed signals, and particularly for the reception and forwarding of frequency multiplexed signals from broadband signals and narrow band signals with a broadband amplifier (AMP) for the amplification of the received broadband signals and for the subsequent forwarding of the amplified broadband signals.
Frequency multiplexed signals are, for example, merged together from broadband and narrow band signals. The broadband and narrow band signals are, as a rule, transmitted within different frequency ranges.
In communication networks, as known for example from U.S. Pat. No. 5,343,240, broadband signals, for example distribution signals such as cable television signals, as well as narrow band signals, for example bi-directional signals such as for cable telephony, are transmitted over a common line. The distribution signals and the bi-directional signals are separated from one another according to frequency, so that they are separated in the receiver by passive filters, for example a high-pass filter for cable television signals and a low-pass filter for cable telephony, and can be fed, for example, to a television, or a telephone modem. On the transmission lines, the distribution signals and the bi-directional signals are amplified in the bi-directional intermediate repeaters. If an intermediate repeater fails, for example because of a power failure, a multitude of end users can neither receive television signals, nor make telephone calls.
It is therefore an objective of the present invention to create an intermediate repeater that can make available at least a minimum of information to the end user sites connected with it even in the event of a is power failure or a failure of the amplification elements.
This objective is resolved according to the invention by an intermediate repeater which includes a first device (HP1, LP1; C1; S1; MAX1) that is connected in series with the broadband amplifier (AMP) and is set to forward the received narrow band signals without amplification by bypassing the broadband amplifier (AMP).
The intermediate repeater according to the invention distinguishes itself in particular by containing a device that can perform a separation by frequency of the received multiplex signals into broadband and narrow band signals, through which, a forwarding of at least a portion of the received signalsxe2x80x94namely the narrow band signals, which are not subject to quality requirements as stringent as those for the broadband signalsxe2x80x94is possible, in the event of a failure of the power supply, or other operational disturbance, of the intermediate repeater.
Narrow band signals, as a rule, are modulated with a known modulation process that is more resistant to interference than the modulation process that is used for the broadband signals. In the event of a failure of an intermediate repeater according to the invention, the is narrow band signals, if necessary, are sent out by the signal source with a strengthened transmission level in order to reroute the line to the next intermediate repeater without substantial attenuation loss. Essentially, with the invention, a telephone connection can also be established and maintained during a failure of an intermediate repeater.
In a preferred embodiment of the invention, a unidirectional amplifier can be used instead of a bi-directional one. This lowers the installation costs as well as the operating costs.
In another embodiment, through exclusive amplification of the broadband signals, the bandwidth to be amplified is smaller, which results in a cost saving in the production of the amplifier, since the linearity requirements of the amplifier can be reduced.